Determination of progressive/regressive isn’t constrained to levying of taxes, and includes how such dollars are spent.
But the tax code portion, the determination of liability, percentages of income/wealth — it’s a huge component of what goes into the calculation of progressive/regressive.
Overall, I would like to see less ‘policy’ implemented through tax law — percentages, deductions, incentives, etc. The original policy objectives are often subverted, unintended consequences.
As for NO tax….
How would you pay for government then? Are there things the government does that are worthwhile?